Disk drives are digital data storage devices which allow host computers to store and retrieve large amounts of data in a fast and efficient manner. A typical disk drive includes a plurality of magnetic recording disks which are mounted to a rotatable hub of a spindle motor and rotated at a high speed. An array of read/write transducers is disposed adjacent to surfaces of the disks to transfer data between the disks and a host computer. The transducers can be radially positioned over the disks by a rotary actuator and a closed loop, digital servo system, and can fly proximate to the surfaces of the disks upon air bearings. The transducers each typically contain a separate read element and write element.
Data is stored within concentric tracks on the disks. The magnetic recording disks are coated with a magnetic material that is capable of changing its magnetic orientation in response to an applied magnetic field. To write data to or read data from a disk, a transducer is positioned above a desired track of the disk while the disk is spinning.
Writing is performed by delivering a write signal having an alternating current to the write element. The write signal creates an alternating orientation magnetic field at a gap portion of the write element that induces magnetic polarity transitions in the magnetic material of the disk, and which thereby creates a data region on the track. The magnetic polarity transitions are representative of the stored data. Reading is performed by sensing magnetic polarity transitions previously written on tracks of the disk with the read element. As the disk spins below the transducer, the magnetic polarity transitions along a track present a varying magnetic field to the read element. The read element converts the magnetic signal into an analog read signal.
As data is written along a track, side lobes of the magnetic field from the write element erase a band of the disk that is adjacent to both sides of the track. When an erase band overlaps a sufficient amount of an adjacent track, any data thereon can become effectively erased, which can be referred to as adjacent track erasure. The spacing between adjacent tracks can be defined so that the erase bands of one track will generally not overlap adjacent tracks. Accordingly, the distance between tracks can be increased to avoid adjacent track erasure, however, increased track spacing can cause a corresponding decrease in the data storage capacity of the disk.